1. Field of the Invention
The present invention relates to an information processing apparatus that takes a plurality of power states, and a method for controlling the information processing apparatus.
2. Description of the Related Art
Techniques for suppressing power consumption of a network-connected information processing apparatus such as a multi function peripheral (MFP) and a printer have heretofore been discussed. Among the known techniques for suppressing the power consumption is one that shifts the information processing apparatus to a low power consumption state if the information processing apparatus has not been operated for a certain time. For further power saving from the low power consumption state, a technique for automatically powering off the information processing apparatus if the information processing apparatus in the low power consumption state has not been operated for a certain time (shutdown shift time) has been known (hereinafter, referred to as an automatic shutdown function; see Japanese Patent Application Laid-Open No. 08-076653).
In the above-described low power consumption state, a power supply to a network interface card (NIC) for receiving packets is maintained to monitor packets transmitted from a computer on the network. If the information processing apparatus returns from the low consumption state to a normal power state to make a response to every packet that the NIC receives, the power consumption of the information processing apparatus eventually becomes high.
A technique called proxy response has been discussed. The proxy response refers to a technique that provides the NIC with a function of responding to a specific packet or packets. With the proxy response, the NIC responds to the specific packet(s) with the information processing apparatus remaining in the low power consumption state (without the information processing apparatus returning to the normal power state). This can reduce the power consumption of the information processing apparatus because the time during which the information processing apparatus is in the low power consumption state increases. If the NIC receives a packet other than the specific packet(s), the NIC can make no proxy response and the information processing apparatus needs to be restored from the low power consumption state to the normal power state. When a packet to which no proxy response can be made is received, the information processing apparatus, which is restored to the normal power supply, makes a response to the packet.
The information processing apparatus that makes a proxy response in the low power consumption state can respond to the specific packet(s) transmitted from an external apparatus while remaining in the low power consumption state. However, the information processing apparatus cannot respond to a packet other than the specific packet(s) while remaining in the low power consumption state. In an environment where the information processing apparatus frequently receives packets to which no proxy response can be made, the information processing apparatus frequently returns from the low power consumption state to the normal power state. In such an environment, the shutdown shift time to elapse before activation of the above-described automatic shutdown function stops being measured each time the information processing apparatus returns to the normal power state. The automatic shutdown function therefore will not be executed despite its existence. As a result, the information processing apparatus keeps failing to enter an off state.